The prior art includes a variety of turbines having integrated generators. The Gamell U.S. Pat. No. 4,293,777 discloses a turbine with a hollow rotor in which are disposed the elements of an electric generator. The Hannan U.S. Pat. No. 4,935,650 discloses a fluid driven rotor with spaced apart ferromagnetic discs which cooperate with cavities of a ferromagnetic stator to generate electrical power. The Cliborn U.S. Pat. No. 2,984,751 discloses a rotor carrying an armature element which cooperates with exteriorly mounted stationary field elements. The Williams U.S. Pat. No. 3,039,007 discloses a turbine wheel having a shaft which mounts a permanent magnet for being rotatably driven inside a stator steel core. The Parker U.S. Pat. No. 2,743,375 discloses a turbo-generator having rotating bladed discs alternating with stationary discs; each of the discs carry cooperating flat radial pole-pieces and windings. The Adkins U.S. Pat. No. 3,157,793 includes stator discs circumferentially disposed about rotor discs which have magnetic poles placed about their peripheries.
One fluid source for exploiting integrated turbine generators is natural gas. At the well head, natural gas may flow from the earth's crust at high pressure to drive a turbine to produce electricity. Hence, electricity is available at no cost on sites such as oil platforms at sea. Turbine generators may also be operated at no cost at pressure reduction stations for natural gas pipelines. Such stations are typically located in metropolitan areas where gas pressure is released from a higher pressure for transportation in the pipeline to a lower pressure for business or residential use.